Quote from Peternam:
Amibroker
Blackwood API
Bracket Trader
Dorman Trading (Service supplier)
CQG Trader API
Cooltrade
Globalfutures.com (Service supplier)
Interactive Brokers API
JSystemTrader
Laser API
Matlab (IB-Matlab)
Multicharts
NinjaTrader
RCG (Service supplier)
Robotictradingsystems.com (CoolTrade)
SierraChart
Stockticker.com
StrategyRunner
Tickquest/Neoticker
Tradebullet
TradingSimulations.com/tsimplus/
Tradelink
Tradevek
ZeroLine Trader
Zulutrade (forex only)
I found this list....

Quote from sheepsucker:
RTS and ORC websites seem full of sales-jargon and not so much hard features.
Quote from alexandermerwe:
Most put so much effort in finding the most professional platform while they lack a robust strategy to trade.
The problem of most traders, I say 99.99%, is that they lack a strategy. Some they do not even know that. They think the solution is a fancy platform.